The black-and-white warbler (Mniotilta varia) is a species of New World warbler, the only member of its genus, Mniotilta.[2] The genus name is from Ancient Greekmnion, "seaweed", and tillo, "to pluck"; Vieillot mistranslated the first word as "moss". The specific varia is from Latinvarius, "variegated".[3]

This species is 14 cm (6 in) long and weighs 11 g (0.39 oz).[4] The summer male black-and-white warbler is boldly streaked in black and white, and the bird has been described as a flying humbug. There are two white wing bars. Female and juvenile plumages are similar, but duller and less streaked.

Its song is a high see wee-see wee-see wee-see wee-see wee-see or weesa weesa weetee weetee weetee weet weet weet. It has two calls, a hard tick, and a soft, thin fsss.[2][4]

The breeding habitat is broadleaved or mixed woodland, preferably in wetter areas. Black-and-white warblers nest on the ground, laying 4–5 eggs in a cup nest.[2]

This bird feeds on insects and spiders, and unlike other warblers, forages like a nuthatch, moving up and down tree trunks and along branches.[4]